Contactor

ABSTRACT

A contact apparatus is provided having a permanent magnet disposed in a region where a fixing contact point is mounted to a fixing contact and a movable contact to which a movable contact point is mounted. An arc generated between both the contact points is moved in a lateral direction by the magnetic force of the permanent magnet and stretched. An arc-extinguishing member which is heated by the arc for generating arc-extinguishing gas is provided such as to surround the fixing contact point and the movable contact point.

This application is a U.S. national phase application of PCTInternational Application PCT/JP00/07149.

TECHNICAL FIELD

The present invention relates to a contact apparatus suitable for arelay of a power load or an electromagnetic switch.

BACKGROUND OF THE INVENTION Background Technique

In a contact apparatus used for opening and closing a power supply of anelectrically running automobile, relatively great DC current as great as100A is switched. In such a contact apparatus, it is difficult toswiftly break the current due to arc generated between contacts when anelectric path is opened. Thereupon, Japanese Patent ApplicationLaid-Open No. H8-45411 for example discloses a contact apparatus havingan insulator which is heated by heat of an arc for generatingarc-extinguishing gas, in which the arc is cooled by thearc-extinguishing gas, thereby enhancing the breaking performance.

However, if the insulator for generating the arc-extinguishing gas ismerely provided, a voltage rising speed of the arc generated betweencontacts is small, and there is a problem that excellent breakingperformance can not always be obtained.

The present invention has been accomplished in view of the aboveproblem, and it is an object of the invention to provide a contactapparatus in which a voltage rise of an arc generated between contactsis abruptly generated to enhance the breaking performance of an electricpath.

BRIEF SUMMARY OF THE INVENTION Disclosure of the Invention

A contact apparatus of the present invention comprises a fixed contacthaving a fixed contact point, a movable contact provided with a movablecontact point which is connected to and separated from the fixed contactpoint, and a driving mechanism for driving the movable contact, whereina permanent magnet is disposed in a vicinity of a region where the fixedcontact point and the movable contact point are located, an arcgenerated when the fixed contact point and the movable contact point areseparated from each other is formed so that arc is moved sideways fromthe opposed region between the fixed contact point and the movablecontact point by magnetic force of the permanent magnet and the arc isstretched.

In the contact apparatus of such a structure, the arc generated betweenthe fixing contact point and the movable contact point when the electricpath is opened is moved sideways by the magnetic force of the permanentmagnet and stretched. The arc length is increased and thus, the arcvoltage rises. With this, the arc is swiftly extinguished, and thebreaking performance of the electric path is enhanced.

In addition to the above, if an arc-extinguishing member made ofinsulative material capable of generating arc-extinguishing gas isprovided in a region near the fixed contact point and the movablecontact point, the arc is cooled by the arc-extinguishing gas. Withthis, the arc voltage further rises, the breaking performance of theelectric path is further enhanced.

The above and other objects and features of the present invention willbe clearer from the following explanation of embodiments with referenceto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an outward appearance of a contactapparatus in an embodiment 1 of the present invention;

FIG. 2 is a front sectional view of the contact apparatus;

FIGS. 3 show an arc-extinguishing member incorporated in the contactapparatus, wherein FIG. 3(a) is a perspective view, and FIG. 3(b) is aperspective view showing a positional relation between thearc-extinguishing member, a fixing contact and a movable contact;

FIGS. 4 show a pair of permanent magnets incorporated in the contactapparatus, wherein FIG. 4(a) is a perspective view, and FIG. 4(b) is aperspective view showing a positional relation between the permanentmagnets and the arc-extinguishing member;

FIG. 5 is a schematic view of an essential portion showing an action ofthe permanent magnets;

FIG. 6 is a schematic view of an essential portion showing an operationstate of the arc generated by the action of the permanent magnets;

FIG. 7 is a schematic sectional view of an essential portion showingmagnetic action generated by current flowing through the fixing contactand the movable contact;

FIG. 8 is a schematic sectional view of an essential portion showing arelation between yoke and current flowing through the fixing contact;

FIGS. 9 show a modification of the arc-extinguishing member, whereinFIG. 9(a) is a partial perspective view, and FIG. 9(b) is a schematicsectional view of an essential portion showing a relation between thearc-extinguishing member and the arc;

FIGS. 10 show another modification of the arc-extinguishing member,wherein FIG. 10(a) is a partial perspective view, FIG. 10(b) is aschematic sectional view of an essential portion showing a relationbetween the arc-extinguishing member and the arc, and FIG. 10(c) is aview showing characteristics of arc voltage in a state shown in FIG.10(b);

FIG. 11 is a partial perspective view showing another modification ofthe arc-extinguishing member;

FIG. 12 is a partially cut-off front sectional view of a contactapparatus according to an embodiment 2 of the invention;

FIG. 13 is a perspective view showing an outer appearance of a contactapparatus in an embodiment 3 of the invention;

FIG. 14 is a front sectional view of the contact apparatus shown in FIG.13;

FIG. 15 is a schematic sectional view of an essential portion showingthe action of the arc in the contact apparatus shown in FIG. 14; and

FIG. 16 is a schematic sectional view of an essential portion showingthe action of the arc when current flows reversely in the contactapparatus shown in FIG. 14.

DETAILED DESCRIPTION OF THE INVENTION Best Mode for Carrying out theInvention Embodiment 1

A contact apparatus according to this embodiment includes a housing 1 ofan outward appearance shown in FIG. 1. The housing 1 comprises syntheticresin molded product. A lower half of the housing 1 is formed as asubstantially rectangular parallelepiped lower housing portion 1 a foraccommodating a driving mechanism 13 therein, and an upper half isformed as an upper housing portion 1 b for accommodating a currentswitching mechanism 11 which will be described later. A longitudinalthickness (in an F-B direction in the drawing) of the upper housingportion 1 b is smaller than that of the lower housing portion 1 a.Vertical wall-like ribs 1 c . . . are formed on opposite ends and anintermediate portion in the lateral direction (in an L-R direction inthe drawing) of front and rear wall surfaces of the upper housingportion 1 b.

Fixing portions 1 d and 1 d are formed on a bottom of the lower housingportion 1 a for fixing the contact apparatus. The fixing portions 1 dand 1 d project sideways (L-R direction) from left and right side walls.Metal sleeves 2 and 2 are press-fitted into centers of the fixingportions 1 d and 1 d. The contact apparatus is fixed by inserting andfastening fixing tools such as bolts (not shown) into the sleeves 2 and2.

A pair of fixing contacts 3 and 3 made of copper materials are assembledinto an upper end of the upper housing portion 1 b such as to projectsideways from left and right side walls of the upper housing portion 1b. A bolt 4, a nut 5 and a spring washer 6 are mounted to an end of eachof the fixing contacts 3 and 3. Using these members 4 to 6, connectionterminals provided on ends of an external electric wiring (not shown)are fixed and connected to the fixing contacts 3 and 3.

As shown in FIG. 2, a portion of each the fixing contact 3 located inthe housing 1 has substantially U-shaped section having terminalconnection portions 3 a extending outward substantially horizontallyfrom centers of left and right sides of the housing 1, connectionportions 3 b bent downward from inner ends of the terminal connectionportions 3 a, and contact fixing portions 3 c extending horizontallysideways from lower ends of the connection portions 3 b. The terminalconnection portions 3 a project sideways from inside of the housing 1,and the bolts 4, the nuts 5 and the spring washers 6 are mounted toouter ends of the terminal connection portions 3 a. Fixing contactpoints 7 and 7 made of silver are jointed to lower surfaces of thecontact fixing portions 3 c and 3 c at locations thereof closer to theends thereof by brazing.

A movable contact 8 made of copper plate is disposed below each of thecontact fixing portions 3 c and 3 c. The movable contact 8 has a lengthfor entirely covering the pair of left and right contact fixing portions3 c and 3 c. The movable contact 8 is provided by brazing at its leftand right opposite ends with movable contact points 9 and 9 made ofsilver.

When the movable contact 8 is driven upward by the driving mechanism 13from the position shown in the drawing, both the movable contact points9 and 9 abut against the fixing contact points 7 and 7 from below. Withthis movement, the pair of left and right fixing contacts 3 and 3 arebrought into conduction through the movable contact 8. That is, acurrent path (which is also called electric path) between both thefixing contacts 3 and 3 is switched by the vertical movement of themovable contact 8. The fixing contacts 3 and 3 and the movable contact 8constitute a current switching mechanism 11. This current switchingmechanism 11 is disposed in the upper housing portion 1 b. The currentswitching mechanism 11 has a space for accommodating the fixing contacts3 and 3, the contact fixing portions 3 c and 3 c and the movable contact8. This space is formed as a current switching chamber 12.

The driving mechanism 13 comprising an electromagnet is accommodated inthe lower housing portion 1 a. The driving mechanism 13 comprises a coilbobbin 15 around which a coil 14 is wound, an upper yoke 16 disposedalong an upper surface of the coil bobbin 15, and a lower yoke 17 forsurrounding an outside of the coil bobbin 15 from a lower surface of thecoil bobbin 15. The lower yoke 17 has a substantially U-shaped section.The coil bobbin 15, the upper yoke 16 and the lower yoke 17 are providedat their central portion with a through hole, a fixing core 18 is fixedto upper portion thereof, and a movable core 19 is disposed below thefixing core 18. A driving shaft 20 passing through the fixing core 18and extending upward is mounted to the movable core 19. Further, areturn spring 21 comprising a compression coil spring is disposedbetween the fixing core 18 and the movable core 19.

The housing 1 is provided with a substantially horizontal firstpartition wall 1 e for partitioning the space of the driving mechanism13 from the upper current switching chamber 12. A synthetic resinconnection portion 22 projecting upward is disposed in a position in thecenter through hole of the first partition wall 1 e. An upper end of thedriving shaft 20 is engaged with a lower wall surface 22 a of theconnection portion 22. With this arrangement, the connection portion 22is vertically moved in unison with the driving shaft 20.

The movable contact 8 passes through the connection portion 22horizontally and is assembled to the connection portion 22. In moredetail, a contact pressure spring 23 comprising a compression coilspring is further provided in the connection portion 22. The movablecontact 8 is held by the connection portion 22 in a state in which acenter region of the movable contact 8 is pushed against an upper wallsurface 22 b of the connection portion 22 by this spring 23.

With this structure, the movable core 19 is absorbed by the fixing core18 and moved upward if the coil 14 is brought into conduction and thecoil 14 is excited. The driving shaft 20, the connection portion 22 andthe movable contact 8 are moved upward in unison with the movable core19. As a result, the pair of left and right movable contact points 9 and9 abut against the fixing contact points 7 and 7 of the fixing contacts3 and 3, and the electric path between the fixing contacts 3 and 3 isclosed. From this state, if the conduction of the coil 14 is stopped,the movable core 19 is moved downward by spring force of the contactpressure spring 23 and the return spring 21. As a result, the movablecontact 8 is also moved downward and the movable contact points 9 and 9are separated from the fixing contact points 7 and 7, the non-conductivestate between the fixing contacts 3 and 3 is switched, and the electricpath is opened.

When the movable contact points 9 and 9 are separated from the fixingcontact points 7 and 7, an arc is generated between the contacts 9 and7. In order to swiftly extinguish the arc to enhance the breakingperformance of the electric path, in the contact apparatus of thisembodiment, an arc-extinguishing member 31 and a permanent magnet 32 arefurther incorporated in the upper housing portion 1 b as will beexplained below.

As shown in FIG. 3(a), the arc-extinguishing member 31 is formed into arectangular parallelepiped box-like shape. In this drawing, a lid forcovering a front surface is omitted. Notched openings 31 a and 31 b areformed in central regions of upper and lower surfaces of thearc-extinguishing member 31. As shown in FIG. 3(b), thearc-extinguishing member 31 is mounted in the upper housing portion 1 bsuch as to surround the contact fixing portions 3 c and 3 c of thefixing contacts 3 and 3 and the movable contact 8. The notched opening31 a of the upper surface of the arc-extinguishing member 31 has such awidth that terminal connection portions 3 a and 3 a of the fixingcontacts 3 and 3 can be inserted. The lower notched opening 31 b of thelower surface has such a width that the connection portion 22 can beinserted.

The arc-extinguishing member 31 is made of insulative material capableof generating arc-extinguishing gas. As described above, if the arc isgenerated when the movable contact point 9 is separated from the fixingcontact point 7, the arc and its periphery is heated to a hightemperature. As the arc is heated, the arc-extinguishing gas isgenerated from the arc-extinguishing member 31, and the arc is cooled bythis gas. As a result, the arc voltage rises, the arc is extinguishedswiftly, and the breaking performance is enhanced.

As the insulative material capable of generating the arc-extinguishinggas, unsaturated polyester or chain compound to which metal hydroxide orhydrate is added is preferable. As the chain compound, nylon 6 or nylon66 is preferable. As the metal hydroxide, magnesium hydroxide ispreferable. By using such materials, it is possible to enhanceinsulative pressure-resistance deterioration characteristics.

FIG. 4(a) shows a pair of permanent magnets 32 and 32 furtherincorporated in the upper housing portion 1 b. Each of the permanentmagnets 32 and 32 is formed into a rectangular parallelepiped plate-likeshape. The permanent magnets 32 and 32 are disposed such as to beopposed to each other in the longitudinal direction (in the F-Rdirection in the drawing) such as to sandwich the arc-extinguishingmember 31. The permanent magnets 32 and 32 are provided at their backsurfaces with yokes 33 and 33 made of metal plates for covering theentire surfaces thereof. The yokes 33 and 33 are provided at theirperipheries with short projections 33 a . . . projecting alongperipheral surface of the permanent magnets 32 and 32.

By fitting the permanent magnets 32 between the projections 33 a . . .relative mounting positions between the permanent magnets 32 and 32 andthe yokes 33 and 33 are held. Further, the yokes 33 and 33 are providedat their upper edges with magnetic path forming portions 33 b . . .projecting in the longitudinal direction beyond the thickness size ofthe permanent magnets 32 and 32. Therefore, each of the yokes 33 and 33is formed into substantially L-shaped in section at a region of themagnetic path forming portion 33 b.

The yoke 33 having the above shape can be mounted to the permanentmagnet 32 using adhesive, but in this embodiment, the yoke 33 isabsorbed and held by the permanent magnet 32 using magnetic force of thepermanent magnet 32. Therefore, in this case, since adhering operationis unnecessary, it is possible to extremely easily assemble theapparatus.

As shown in FIG. 4(b), the permanent magnets 32 and 32, to which theyokes 33 and 33 are mounted, are incorporated in the upper housingportion 1 b such that they are located at positions along a frontsurface lid and a rear surface wall of the box-like arc-extinguishingmember 31, respectively. At that time, the magnetic path forming portion33 b of the yoke 33 on the front surface side and the magnetic pathforming portion 33 b on the rear surface side are superposed on eachother and assembled. With this design, the front and rear permanentmagnets 32 and 32 are magnetically mutually connected through themagnetic path forming portions 33 b and 33 b which are superposedvertically. As shown in FIG. 2, the magnetic path forming portions 33 bpass between the terminal connection portion 3 a and the contact fixingportion 3 c of each of the fixing contacts 3 and 3, i.e., through theU-shaped portion in the longitudinal direction.

As shown in FIG. 5, the permanent magnets 32 and 32 are magnetized suchthat one of surfaces of the permanent magnets 32 and 32 opposed to eachother while sandwiching the accommodating space for the fixing contactpoint 7 and the movable contact point 9 is the north pole, and the othersurface is the south pole. In the contact apparatus of the embodiment,it is assumed that DC current is allowed to flow between both the fixingcontacts 3 and 3 through the movable contact 8. In this case, adirection of the current is determined in a constant direction. Whenthis direction is shown with a solid arrow, the permanent magnets 32 and32 are formed such that when the electric path is opened and the arc 34is generated between the contact points 7 and 9, magnetic action formoving the arc in a direction toward ends of the fixing contact 3 andthe movable contact 8 is generated in the arc 34.

With this structure, if the arc 34 moved to the ends of the fixingcontact 3 and the movable contact 8, as shown in FIG. 6, since the abovemagnetic force is also applied, the arc 34 is stretched to draw a curve.In this contact apparatus, since the DC current is switched, thedirection of the current flowing through the left and right arcs 34 and34 are vertically opposite. Therefore, the left and right arcs 34 and 34are simultaneously moved toward the opposite ends of the fixing contacts3 and 3 and the movable contact 8 and stretched.

Since the arc 34 is stretched, the arc voltage rises. The arc 34 iscooled also by the arc-extinguishing gas generated from thearc-extinguishing member 31, the arc voltage further rises. As a result,the arc is swiftly extinguished, and current break is carried out athigh speed.

Each of the fixing contacts 3 and 3 in this embodiment is formed intothe substantially U-shaped as described above. With this design, asshown in FIG. 7, directions (direction of→) of current flowing throughthe contact fixing portions 3 c and 3 c of the fixing contacts 3 and 3and the movable contact point 9 are in parallel and opposite from eachother. Therefore, magnetic field generated in accordance with thedirection of the current is strengthened and applied to the arc 34generated between the contact points 7 and 9. As a result, the arc 34swiftly moves the contact fixing portions 3 c and 3 c and the movablecontact point 9 toward the ends. Therefore, with this design also, thebreaking characteristic of the electric path is further enhanced.

In this embodiment, the magnetic path forming portions 33 b of the yoke33 mounted to the permanent magnets 32 and 32 pass through the U-shapedportions of the fixing contacts 3 and 3 and are positioned. With thisdesign, as shown in FIG. 8, magnetic flux generated from current(current flowing through the terminal connection portion 3 a of thefixing contact 3) flowing in the same direction as the movable contact 8of the current flowing through the fixing contact 3 is absorbed by themagnetic path forming portion 33 b of the yoke 33. As a result, magneticflux applied between the contact points 7 and 9 is increased, the arc 34generated between the contact points 7 and 9 swiftly moves toward theend. Therefore, with this design also, the breaking performance of theelectric path is further enhanced.

As explained with reference to FIG. 6, the arc 34 generated between thecontact points 7 and 9 moves toward the ends of the terminal connectionportion 3 a of the fixed contact and the movable contact 8, and arecurved sideways and stretched. A side wall surface 31 c of thearc-extinguishing member 31 located in the moving direction of the arc32 can be provided with a plurality of slits 31 d . . . as shown in FIG.9(a).

With this structure, as shown in FIG. 9(b), the arc 34 swelling towardthe side wall surface 31 c further swells into the slits 31 d. Thus, thearc length is further extended, the arc voltage is increased, and thebreaking performance is further enhanced.

As shown in FIG. 10(a), a plurality of metal plates 35 . . . may bemounted to the side wall surface 31 c of the arc-extinguishing member 31by a method such as integral forming. With this structure, as shown inFIG. 10(b), the arc 34 pumps and moves to the metal plates 35 . . . . Asshown in FIG. 10(c), the arc voltage rises by a value corresponding tocathode drop voltage and anode drop voltage generated in each metalplate 35. With this feature also, the breaking performance of theelectric path can further be enhanced.

As shown in FIG. 11, the side wall surface 31 c of the arc-extinguishingmember 31 may be provided with a plurality of projections 31 e. Withthis structure, since the surface area of the arc-extinguishing member31 receiving heat of the arc 34 is increased, the amount of thearc-extinguishing gas generated is increase, which also enhance thebreaking performance of the electric path.

Embodiment 2

A contact apparatus according to another embodiment of the presentinvention will be explained with reference to FIG. 12. Members havingthe same functions as those of the contact apparatus of the previousembodiment 1 are designated with the same symbols, and detailedexplanation thereof is omitted. The same is applied to the subsequentembodiments.

In this contact apparatus of the present embodiment, the pair of leftand right fixing contact points 7 and 7 and the movable contact points 9and 9 which are opposed to the former contacts from below are providedat locations closer to a center line of the housing 1 compared to thatof the previous embodiment 1. With this structure, a length of each thecontact fixing portion 3 c from the fixing contact point 7 to the end islong, and this portion is formed as an arc running portion 3 d.Similarly, the movable contact 8 is provided at outer sides from themounted positions of the movable contact points 9 and 9 with long arcrunning portions 8 a and 8 a.

In the contact apparatus of such a structure, the arc generated betweenthe contact points 7 and 9 moves sideways on the arc running portion 3 dand 8 a by the magnetic force of the permanent magnet 32 and then, thearc is curved from the end and stretched. As explained with reference toFIG. 7, magnetic field generated by current flowing through the contactfixing portions 3 c and 3 c of the fixing contacts 3 and 3 and themovable contact point 9 is added to the movement on the arc runningportions 3 d and 8 a, and as explained with reference to FIG. 8, themagnetic flux generated from the current flowing through the terminalconnection portion 3 a of the fixing contact 3 is absorbed by themagnetic path forming portion 33 b of the yoke 33, and the magnetic fluxbetween the contact points 7 and 9 is increased, the arc is generatedwithin an extremely short time and reaches the end immediately and isstretched as described above.

A distance between the arc and the contact points 7 and 9 at thatposition becomes long in accordance with the length of the arc runningportions 3 d and 8 a. Therefore, the contact points 7 and 9 areprevented from being heated to a high temperature by heat of the arc. Asa result, the breaking performance of the electric path is enhanced likethe previous embodiment, and even of the switching of the electric pathis repeated, a wear amount of the contact points 7 and 9 caused by theswitching is reduced, and the life of the contact is enhanced.

Embodiment 3

A contact apparatus of another embodiment of the present invention willbe explained with reference to FIGS. 13 to 16.

As shown in FIG. 13, the housing 1 of this contact apparatus comprisesthe lower housing portion 1 a and the upper housing portion 1 b providedon the lower housing portion 1 a. The upper housing portion 1 b has athickness in the longitudinal direction smaller than that of the lowerhousing portion 1 a. However, the front and rear wall surfaces of theupper housing portion 1 b are not provided with the ribs 1 c . . . shownin FIG. 1, but are formed as flat surfaces. The permanent magnet 32having the yoke 33 having the same shape as that of the previousembodiment is mounted to each of the surfaces from outside. That is, theupper housing portion 1 b is formed with through holes in thelongitudinal direction, and the magnetic path 33 b of the yoke 33 passesthrough each of the through holes, and the pair of permanent magnets 32and 32 are mounted to the upper housing portion 1 b from front and back.

In FIG. 13, a reference number 40 represents a lead wire to beelectrically connected to the coil 14. The lead wire 40 is pulled outthrough an outlet hole 1 g formed in an outer wall if of a side of thelower housing portion 1 a.

As shown in FIG. 14, the driving mechanism 13 comprising aelectromagnetic apparatus having substantially the same structure asthat of the embodiment 1 is accommodated in the lower housing portion 1a. However, in this driving mechanism 13, a cylinder 16 a suspendeddownward in a cylindrical shape into a center region in the upper yoke16 is formed. This cylinder 16 a functions in the same manner as that ofthe fixing core 18 shown in FIG. 2. In this driving mechanism 13, thedriving shaft 20 fixed at its lower end to the movable core 19 andextending upward, and the connection portion 22 for holding the movablecontact 8 are integrally formed by synthetic resin.

A lateral length of a first partition wall 1 e for partitioning thedriving mechanism 13 from the current switching chamber 12 is setshorter than a size between the outer walls 1 f and 1 f so that a spaceis formed between the left and right outer wall 1 f and 1 f. The housing1 is further provided with second partition walls 1 h and 1 h suspendingdownward from left and right opposite ends of the first partition wall 1e. The driving mechanism 13 is disposed between the second partitionwalls 1 h and 1 h. Vent passages 1 j and 1 j which are in communicationwith the current switching chamber 12 are formed between the secondpartition walls 1 h and 1 h and the left and right opposite side outerwall 1 f and 1 f of the housing 1.

The lower yoke 17 is formed with notched openings 17 a and 17 a atheight positions corresponding to lower ends of the second partitionwalls 1 h and 1 h. Therefore, The vent passages 1 j and 1 j are incommunication also with the space of the driving mechanism 13 throughthe notched openings 17 a and 17 a. A right outer wall if of the housing1 is formed with an outlet hole 1 g for pulling out the lead wire 40.The vent passage 1 j is in communication with outside through the outlethole 1 g.

In the upper housing portion 1 b, the pair of fixing contacts 3 and 3and the movable contact 8 formed in substantially the same manner asthose in the previous embodiment are disposed. In the current switchingchamber 12 in which these members are disposed, the arc-extinguishingmember 31 is not disposed. Instead, the housing 1 itself is made ofmaterial which generates the arc-extinguishing gas such as nylon 6 ornylon 66 to which magnesium hydroxide is added, PBT or unsaturatedpolyester.

The contact fixing portions 3 c and 3 c of the fixing contacts 3 and 3and the movable contact 8 are provided with arc running portions 3 d, 3d, 8 a and 8 a extending laterally from mounted positions of the fixingcontact points 7 and 7 and the movable contact points 9 and 9 in thesame manner as that of the previous embodiment. A length of each of thearc running portions 3 d and 3 d of the contact fixing portion 3 c and 3c is set longer than the arc running portion 8 a and 8 a of the movablecontact 8.

In the housing 1 of the contact apparatus of this embodiment, aseparation projection 1 k suspended downward is provided on a regionbetween the connection portions 3 b and 3 b of the pair of left andright fixing contacts 3 and 3.

In the contact apparatus of this structure, as shown in FIG. 15, the arc34 generated between the contact points 7 and 9 when the electric pathis opened moves sideways toward ends of the contact fixing portion 3 cand the movable contact 8 by the magnetic force of the permanent magnet32 like the previous embodiment. In this case, since the end of thecontact fixing portion 3 c is located outer side from the movablecontact 8, when the arc 34 moved to a position between both the ends,the arc is inclined and becomes longer. Thereafter, the arc 34 isfurther curved and deformed, the arc length is further increased. As thearc 34 is stretched, the arc voltage abruptly rises and with this, thearc 34 is swiftly extinguished and the breaking is carried out at highspeed.

In this embodiment, the lengths of the arc running portions 3 d and 3 dof the contact fixing portions 3 c and 3 c and the arc running portions8 a and 8 a of the movable contact 8 are different from each other.Therefore, it is easy and swiftly to stretch the arc 34 in the processof movement of the arc 34, and the breaking characteristic of theelectric path is further enhanced.

When arc running portion 3 d of the contact fixing portion 3 c is formedlonger than the arc running portion 8 a of the movable contact 8, thecurved deformation of the arc 34 has directional property in diagonallydownward direction. With this, air existing in the side space in thecurrent switching chamber 12 is heated by the arc 34, and the pressurerises. The air (arc gas, hereinafter) whose pressure is increased alsohas directional property along the curved direction of the arc 34.

In this case, in the contact apparatus of this embodiment, as explainedwith reference to FIG. 14, the first partition wall 1 e is not closed inthe above direction and is in communication with the vent passage 1 j.With this structure, the stretching space toward the above direction issecured. Therefore, the arc 34 can easily be stretched toward the ventpassage 1 j. Further, the arc gas flows toward the lower housing 1 bfrom the current switching chamber 12 through the vent passage 1 j.

A lower end of the vent passage 1 j is in communication with outsidethrough the outlet hole 1 g through which the lead wire 40 is pulledout. The lower end is also in communication with the space in which thecoil 14 is disposed through the notched opening 17 a of the lower yoke17. Thus, the space around the coil 14 is utilized as a space forreleasing the arc gas. As a result, the pressure rise of the arc gas inthe current switching chamber 12 is suppressed to a small value. Withthis structure, even if the housing 1 is substantially hermeticallyclosed except the outlet hole 1 g, the housing 1 is prevented from beingswelled and deformed by the arc gas.

The contact apparatus is used for switching the DC current as describedabove, and the direction of the current is constant. However, in thiskind of contact apparatus, a great current flows in the above direction,and small current flows in the opposite direction in some cases. A pairof left and right arcs generated between the contact points 7 and 9 whenthe current in the opposite direction flow move in a directionapproaching each other by the magnet force of the permanent magnet 32unlike the above explanation.

The separation projection 1 k is provided between the fixing contacts 3and 3 so that the arc is not kept and the electric path is reliablybroken even in such a case also. That is, as shown in FIG. 16, if thearcs 34 and 34 generated in the contact points 7 and 9 move toward thecenter and curved such as to approach further, and if the arc 34 ischanged to the arc 34 a extending between the connection portions 3 band 3 b of the fixing contacts 3 and 3, the arc 34 a is stretchedbypassing the separation projection 1 k. Therefore, the arc voltage ofsuch a shape becomes sufficiently high, the arcs 34 and 34 between thecontact points 7 and 9 are extinguished to cut off the electric path.

The preferred embodiments of the present invention are explained above,the present invention is not limited to the embodiments except the scopeof the invention, and the invention can variously be changed withoutdeparting from the spirit and scope of the invention.

For example, although the two permanent magnets 32 and 32 are opposedand disposed in parallel to each other in each of the embodiments, theinvention is not limited to this structure only if the permanent magnetsare disposed such that the magnetic field is formed at least between thecontact points 7 and 9.

In the embodiments 1 and 2, the arc-extinguishing member 31 is formedinto a rectangular parallelepiped box-like shape, the invention is notlimited to this, and the arc-extinguishing member 31 may have only asurface perpendicular to the moving direction of the arc 34 between thecontact points 7 and 9 for example.

The fixing contact 3 is of substantially U-shape in each of the aboveembodiments, the invention is not limited to this, and the fixingcontact 3 may have any shape only if at least the fixing contact point 7and the movable contact point 9 can be connected to and separated fromeach other.

In the embodiment 3, the arc running portion 3 d of the fixing contact 3is longer than the arc running portion 8 a of the movable contact 8, theinvention is not limited to this, and the arc running portion 8 a of themovable contact 8 may be longer than the arc running portion 3 d of thefixing contact 3.

The arc running portion 3 d of the fixing contact 3 and the arc runningportion 8 a of the movable contact 8 in the embodiments 2 and 3 are inparallel to each other, the arc running portions 3 d and 8 a may not bein parallel such that they are separated from each other toward the end.In this case, since the arcs are stretched during the course of movementof the arc running portions 3 d and 8 a, the breaking characteristic isfurther enhanced.

Industrial Applicability

As described above, the contact apparatus of the present invention hasexcellent breaking characteristic of the electric path by providing thepermanent magnet and the arc-extinguishing member. Therefore, thecontact apparatus can preferably be used for an electromagneticswitching apparatus for opening and closing great DC current such as apower supply of an electrically running automobile, a power load relayand the like.

What is claimed is:
 1. A contact apparatus comprising: a fixed contacthaving a fixed contact point, a movable contact provided with a movablecontact point which is connected to and separated from the fixed contactpoint, both the fixing contact and the movable contact providing runningportions having different lengths with respect to the other, a drivingmechanism for driving the movable contact, the driving mechanism havinga permanent magnet disposed in a vicinity of a region where the fixedcontact point and the movable contact point are located, an arcgenerated when the fixed contact point and the movable contact point areseparated from each other is moved in a lateral direction with respectto the fixed contact point and movable contact point by magnetic forceof the permanent magnet, and an arc-extinguishing member made ofinsulative material capable of generating arc-extinguishing gas isprovided in a region near the fixed contact point and the movablecontact point.
 2. The contact apparatus according to claim 1, whereinthe insulative material is unsaturated polyester.
 3. The contactapparatus according to claim 1, wherein the insulative material is achain compound to which metal hydroxide or hydrate is added.
 4. Thecontact apparatus according to claim 3, wherein the chain compound isnylon 6 or nylon
 66. 5. The contact apparatus according to claim 3,wherein the metal hydroxide is magnesium hydroxide.
 6. The contactapparatus according to claim 1, wherein the arc-extinguishing memberincludes a slit in a region corresponding to a path of the arc movement.7. The contact apparatus according to claim 1, wherein thearc-extinguishing member includes a metal plate in a regioncorresponding to a path of the arc movement.
 8. The contact apparatusaccording to claim 1, wherein the arc-extinguishing member includes aprojection in a region corresponding to a path of the arc movement. 9.The contact apparatus according to claim 1, wherein an end of the fixedcontact point is formed into a substantially U-shape in which an end ofa contact fixing portion to which a fixing contact point is mounted andan end of a terminal connection portion which is opposed to this contactfixing portion and is in substantially parallel to the contact fixingportion are connected to each other through a connection portion. 10.The contact apparatus according to claim 1, further comprising a yokefor mutually connecting the pair of permanent magnets magnetically. 11.The contact apparatus according to claim 10, wherein an end of the fixedcontact point is formed into a substantially U-shape in which an end ofa contact fixing portion to which a fixing contact point is mounted andan end of a terminal connection portion which is opposed to this contactfixing portion and is in substantially parallel to the contact fixingportion are connected to each other through a connection portion, and atleast a portion of the yoke is disposed on the substantially U-shapeportion of the fixing contact.
 12. The contact apparatus according toclaim 10, wherein the yoke comprises two yoke parts each having L-shapedsection.
 13. The contact apparatus according to claim 12, wherein thetwo yoke parts are held by suction force of the permanent magnet. 14.The contact apparatus according to claim 1, wherein at least one of thefixing contact and the movable contact having an arc running portionextending in a direction in which the arc is moved by the force of thepermanent magnet.
 15. The contact apparatus according to claim 1,further comprising: a housing having a first partition wall forpartitioning the driving mechanism from a current switching chamber inwhich the fixing contact point and the movable contact point arelocated, a second partition wall is provided in a region between thedriving mechanism at a location closer to the driving mechanism than thefirst partition wall and an outer wall of the housing, and a ventpassage which extends to the current switching chamber is formed betweenthe second partition wall and the outer wall of the housing.
 16. Thecontact apparatus according to claim 1, wherein a pair of fixingcontacts are disposed such as to be opposed to opposite ends of themovable contact, movable contact points respectively provided onopposite ends of the movable contact are connected to and separated froma fixing contact points provided on each of the fixing contact, ahousing is provided a region between both the fixing contacts with aseparation projection for spreading the arc when the arc is generatedbetween both the fixing contacts.